Aim: Kidney transplantation is the best treatment option in end-stage renal disease patients. Despite advances in immunosuppressive treatment modalities rejection has serious adverse effects on post-transplant allograft survival. Gold standard in the diagnosis of allograft dysfunction is renal allograft biopsy. In our study, we aimed to evaluate the kidney allograft biopsies and find out the effect of the treatment that are decided according to the pathology results on long-term allograft survival in kidney transplant recipients.
Materials and Methods: The data of 190 patients who underwent renal transplantation between January 2012 and January 2022 and followed up in the Baskent University Faculty of Medicine Ankara Hospital Transplantation unit were retrospectively evaluated.
46 of the patients (24.2%) were female and 144 (75.8%) were male, with a mean age of 38.8±12.1 years. Tacrolimus is the most preferred drug in maintenance immunosuppressive therapy (n=133, 70.1%), followed by Cyclosporine (n=47, 24.7%). The mean creatinine value of the patients before biopsy was 2.29±1.1 mg/dl, and the mean proteinuria amount (as the spot urine protein-creatinine ratio) was 1.46±2.4. An increase of 1 mg/dl in creatinine and 1 unit in urine protein/creatinine ratio during biopsy showed 1.4 times higher relative risk of allograft loss. The most common diagnosis in pathology results was cellular and/or antibody-mediated acute rejection. There was a positive correlation between duration and treatment outcomes in terms of creatinine and proteinuria. In patients who had both cellular and antibody-mediated rejection, allograft survival is worse than cellular or antibody-mediated rejection alone. While the mean creatinine before biopsy was 2.2±1 mg/dl (median 1.9 mg/dl) in cases without CNI toxicity, this value was 2.7±1.5 mg/dl (median 2.2 mg/dl) in patients with CNI toxicity (p=0.05; Mann Whitney U). Likewise, the median value of protein-creatinine ratio before biopsy was 1.1 in the group with toxicity, while it was 0.3 in the group without CNI toxicity (p<0.001). These results prove the nephrotoxic effect of CNI drugs. In our study, CNI toxicity was found in 14.9% of patients using Cyclosporine and in 10.5% of patients using Tacrolimus. In addition, a positive correlation was found between the number of sclerotic glomeruli and the creatinine and proteinuria results at the first, sixth, and 12th months. Serum creatinine levels in the 6th and 12th month and proteinuria in the 12th month ​​were found to have a significant effect on allograft survival. Allograft loss was observed in 51 (26.8%) of 190 patients who underwent renal allograft biopsy. The median survival time for patients undergoing renal allograft biopsy was 2154±291.5 days. In terms of allograft survival, the cumulative survival rate in the first year is 77.7%, while the cumulative survival rate in the fifth year is 51% in kidney transplant recipients who experienced at least one rejection epizode. Risk factors that are significantly associated with allograft loss are the presence of TMA, the presence of recurrent glomerular disease, the presence of CNI toxicity, and the presence of cellular rejection.
Conclusion: In conclusion, acute rejection epizodes significantly lower long-term kidney graft survival rates. Early diagnosis and intensive treatment is necessary especially in patients who are evaluated to have high risk prior to transplantation.